A vehicle may include a vacuum system to operate or to assist in the operation of various devices. In particular, vacuum may be a way to assist a driver applying vehicle brakes or other vacuum operated devices. Vacuum may be provided in some vehicle via a vacuum pump because the engine operates frequently with a positive intake manifold pressure. Some vacuum pumps may be electrically driven (typically on-demand) by a motor while others are mechanically driven (typically operated continuously) via the vehicle's engine. Vane vacuum pumps have the capacity to produce vacuum over long vacuum pump life cycle. However, if the vane vacuum pump is not properly lubricated the vane vacuum pump life cycle may be reduced and the vane vacuum pump may not be able to produce a desired level of vacuum.
The inventor herein has recognized the above-mentioned disadvantages and has developed an engine vacuum system, comprising: an engine including a crankcase vent and an oil separator located along the crankcase vent; and a vacuum pump in fluidic communication with the engine and a vacuum consumer, a vacuum pump inlet port in fluidic communication with a passage entering an interior of the engine, the passage absent an oil pump along its length.
By directing gases from within an engine's oiled compartment to a vacuum pump, it may be possible to lubricate the vacuum pump with engine oil that may be entrained within the gases. Further, the gases may be returned to an interior portion of the engine so that they may be subsequently combusted by the engine (or the oil mist may return as liquid oil to the engine oil). In this way, it may be possible to lubricate the vacuum pump without an oil pump directing oil to the vacuum pump. In one example, gases from the engine may be drawn to the vacuum pump inlet only in response to a vacuum level of a vacuum reservoir exceeding a threshold vacuum level. Consequently, gas flow from the engine to the vacuum pump inlet may occur only during select conditions.
The present description may provide several advantages. In particular, the approach can improve the operation of a vacuum pump that has oil wetted seals. Further, the approach can reduce vehicle emissions for vehicles that have vacuum pumps. Further still, the vacuum pump may be lubricated without an oil pump supplying oil to the vacuum pump.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.